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Am I doing this right?
10-01-2017, 05:59 PM
Post: #1
Am I doing this right?
I have the H-bot set up and running but it seems to not be moving as smooth as the example videos. I'm curious if I am doing something wrong.

The main problem, is that when I connect my phone to the robot, it tracks the puck, but does not seem to attack or move properly.

Here is a link to a video of the test pattern...
Video of test pattern

A couple things to note...
  • The table recommended on your site is not available for purchase in the US ( I looked everywhere)
  • The closest table I could find is a bit wider than the recommended. I cut new rods to acomodate this.
  • I have not modified any of the arduino code (only uploaded latest from github)

Any assistance is greatly appreciated.
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10-02-2017, 08:58 AM
Post: #2
RE: Am I doing this right?
Some tips:
- The blue support on the sides of the table are (very likely) confusing the APP. Do not use the same colour for different elements but the robot, otherwise you will have this kind of problem.
- The belt is a little bit loose.
- Is the Pusher touching the playing surface?
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10-02-2017, 02:54 PM
Post: #3
RE: Am I doing this right?
(10-02-2017 08:58 AM)jpedroc Wrote:  Some tips:
- The blue support on the sides of the table are (very likely) confusing the APP. Do not use the same colour for different elements but the robot, otherwise you will have this kind of problem.

That's not a problem. I can re-print them. (amusingly that is the color that was sent to us when we ordered the kit).
When I run the app, the puck and pusher appear to be detected OK. The biggest issue I'm having is movement.

(10-02-2017 08:58 AM)jpedroc Wrote:  - The belt is a little bit loose.

I thought so too, but when looking at the documentation, the recommendation was to have a loose belt. I didn't have much different results when using a tighter belt.

(10-02-2017 08:58 AM)jpedroc Wrote:  - Is the Pusher touching the playing surface?

The pusher is not touching the playing surface, it is about 1mm off the surface.
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10-03-2017, 08:43 AM (This post was last modified: 10-03-2017 08:48 AM by JJrobots JP.)
Post: #4
RE: Am I doing this right?
If the calibration of the playing surface is perfect, there should not be problems with any blue feature outside the playing "area" but that might be a likely problem if the camera sees any blue-ish object on the playing court beside the robot :-\

Does the robot make the "test pattern" correctly? (there is a video in the assembly guide showing the movements the robot should make.)

Beside all of this.
How much did you reduce the metal bars lenght? There is one thing you will need to modify. It is not related with the lack of movement of the robot, but has to be done: That will increase the accuracy of the robot movements

Inside the configuration.h file, the dimension parameters are set:
Code:
// This is the center of the table. All units in milimeters
// This are the dimensions of the official air hockey table Exploter from Buffalo
#define TABLE_LENGTH 895
#define TABLE_WIDTH 435
#define ROBOT_CENTER_X TABLE_WIDTH/2   // Center of robot.
#define ROBOT_CENTER_Y TABLE_LENGTH/2

// Absolute Min and Max robot positions in mm (measured from center of robot pusher)
#define ROBOT_MIN_X 60
#define ROBOT_MIN_Y 58
#define ROBOT_MAX_X TABLE_WIDTH-ROBOT_MIN_X
#define ROBOT_MAX_Y ROBOT_CENTER_Y-80[/i]

Set the correct dimensions of the new air hockey table.

One last thing: trim the current output of the stepper motor drives using a screwdriver. In the assembly guide there is info about how to do that. There is a small screw on top of the stepper motor drivers, rotate it sligthly in order to get more power from them (just a little bit)

Let us know how it goes!
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10-03-2017, 01:54 PM (This post was last modified: 10-03-2017 02:03 PM by tpaschedag.)
Post: #5
RE: Am I doing this right?
(10-03-2017 08:43 AM)jpedroc Wrote:  Does the robot make the "test pattern" correctly? (there is a video in the assembly guide showing the movements the robot should make.)

I looked on this guide and I don't see any videos of the test pattern. Could you help me find it?

I found it here: https://www.jjrobots.com/air-hockey-robo...ide-v-1-0/
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10-05-2017, 06:05 PM
Post: #6
RE: Am I doing this right?
(10-03-2017 08:43 AM)jpedroc Wrote:  If the calibration of the playing surface is perfect, there should not be problems with any blue feature outside the playing "area" but that might be a likely problem if the camera sees any blue-ish object on the playing court beside the robot :-\

Does the robot make the "test pattern" correctly? (there is a video in the assembly guide showing the movements the robot should make.)

Beside all of this.
How much did you reduce the metal bars lenght? There is one thing you will need to modify. It is not related with the lack of movement of the robot, but has to be done: That will increase the accuracy of the robot movements

Inside the configuration.h file, the dimension parameters are set:
Code:
// This is the center of the table. All units in milimeters
// This are the dimensions of the official air hockey table Exploter from Buffalo
#define TABLE_LENGTH 895
#define TABLE_WIDTH 435
#define ROBOT_CENTER_X TABLE_WIDTH/2   // Center of robot.
#define ROBOT_CENTER_Y TABLE_LENGTH/2

// Absolute Min and Max robot positions in mm (measured from center of robot pusher)
#define ROBOT_MIN_X 60
#define ROBOT_MIN_Y 58
#define ROBOT_MAX_X TABLE_WIDTH-ROBOT_MIN_X
#define ROBOT_MAX_Y ROBOT_CENTER_Y-80[/i]

Set the correct dimensions of the new air hockey table.

One last thing: trim the current output of the stepper motor drives using a screwdriver. In the assembly guide there is info about how to do that. There is a small screw on top of the stepper motor drivers, rotate it sligthly in order to get more power from them (just a little bit)

Let us know how it goes!
  • The robot does not make the test pattern like in the guide at all. (Watch this video)
  • I didn't reduce, I increased the metal bars as this table is a little wider than the recommended table.
  • I updated the code as suggested with the table dimensions to match my table.
  • Without the belt on, the pusher moves quite easily. There doesn't seem to be any friction.

Is it possible these motors are just not powerful enough for the wider table?
It moves, but why doesn't it go all the way to the end like the test pattern in your video?
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10-05-2017, 06:49 PM
Post: #7
RE: Am I doing this right?
Yes, you are problably right, you will need to increase the power delivered by the motors. There are several options:
1) Adjust the output current of the A4988 stepper motor drivers (rotating the small screw on the top): You can get up to 20% more power doing this.
2) Increase the Voltage of the whole system (you can connect to the Arduino a power supply of 15 volts instead of the regular 12V) But! keep the FAN always blowing over the electronics. They get hot
3) Replace the stepper motor drivers A4988-> DRV8825 (more info here:http://reprap.org/wiki/A4988_vs_DRV8825_Chinese_Stepper_Driver_Boards). The DRV delivers more current than the A4988 increasing the power of the motors
4) Reduce the accelerations of the robot (via Arduino CODE). The stepper motors are skipping steps as they can not move as fast as required.
5) Replace the stepper motors: short NEMA17 to long NEMA17 (like these ones:http://www.ebay.co.uk/itm/Longs-Motor-5pcs-nema17-stepper-motor-75oz-in-wire-1m-cable-1-5A-for-3D-cnc-/201622915336?hash=item2ef1a98908:g:-PwAAOSwyKxXhvXk)
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10-05-2017, 08:17 PM
Post: #8
RE: Am I doing this right?
Thank you for the info, In my journey I think I have also discovered that the problem may be that the lateral tubes are just too heavy. I could only find solid bars at my local hardware store. I didn't think anything of it but it seems these stepper motors are rather sensitive. We have reached out to a local shop that may have longer aluminum tubes like the ones in the kit. I'm hoping thats the issue.
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10-05-2017, 09:54 PM
Post: #9
RE: Am I doing this right?
(10-05-2017 08:17 PM)tpaschedag Wrote:  Thank you for the info, In my journey I think I have also discovered that the problem may be that the lateral tubes are just too heavy. I could only find solid bars at my local hardware store. I didn't think anything of it but it seems these stepper motors are rather sensitive. We have reached out to a local shop that may have longer aluminum tubes like the ones in the kit. I'm hoping thats the issue.

Yes. Steel is too heavy. If you have access to carbon fibre tubes, they might work too.
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10-09-2017, 03:21 PM
Post: #10
RE: Am I doing this right?
(10-05-2017 09:54 PM)jpedroc Wrote:  Yes. Steel is too heavy. If you have access to carbon fibre tubes, they might work too.

You were right! Getting full range of motion with the aluminum tubes! Thank you!
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